1. Field of the Invention
The invention relates to oil-in-water emulsions of polydimethylsiloxanes having aminoalkyl groups and the use thereof.
2. Background Art
Solvent-based compositions based on amino-functional polydimethylsiloxanes which are used, for example, as water-repellant care compositions are known. U.S. Pat. No. 6,596,060, Atofina, P. Michaud, describes a water-repellant composition which comprises an organopolysiloxane having at least one aminated group and 85-99% by weight of isopropanol. Solvent-based compositions based on (amino-functional) organopolysiloxanes are generally distinguished by a very good water-repellant effect on a very wide range of substrates but are no longer contemporary both in terms of increased environmental awareness with respect to volatile organic compounds (VOCs) and also from the point of view of health. Aqueous compositions will in general therefore increasingly replace solvent-based systems in the future.
Aqueous compositions which contain amino-functional organopolysiloxanes are known. Such compositions are used, for example, for the water-repellant treatment of natural and/or synthetic textile fibers, for the water-repellant treatment of building materials, as a component of polish compositions and as a component of cosmetic formulations. Conventional aqueous compositions which contain amino-functional organopolysiloxanes are known to a person skilled in the art in the form of oil-in-water or water-in-oil emulsions. These emulsions may be present in the form of macroemulsions or microemulsion, and are stabilized, as a rule, by conventional nonionic, anionic, cationic, or amphoteric emulsifiers or by silicone/polyether copolymer emulsifiers.
DE 4328917, Wacker-Chemie GmbH, M. Geck, describes a process for the preparation of microemulsions based on amino-functional organopolysiloxanes, in which organopolysiloxane, conventional emulsifier, water, optionally a cosurfactant and optionally an acid, are combined in any desired sequence and mixed. However, the presence of nonionic, anionic, cationic or amphoteric emulsifiers in these aqueous compositions which contain amino-functional organopolysiloxanes has a considerable, sometimes even drastic, effect on the water-repellant properties of such emulsions in the application.
Aqueous compositions which contain amino-functional organopolysiloxanes and which dispense with the use of the abovementioned conventional emulsifiers are also known. GB 1199501 describes water repellants, in particular for glass surfaces, which contain isopropanol, water and a reaction product of a hydroxyl-terminated, basic nitrogen-containing organopolysiloxane with organic or inorganic acids. However, the aqueous dilutions of these water repellants do not have sufficient stability of the active substance.
EP 1008616 A describes w/o emulsions which contain amino-functional organopolysiloxanes. Such emulsions have the disadvantage that they have a predetermined composition and cannot be diluted with water.
EP 1031593 A describes a composition which consists of a mixture of water-soluble, amino-functional silicon compounds substantially free of alkoxy groups, water, optionally alcohol and optionally acid. The water-repellant effect of the composition is greatly limited by the use of water-soluble (partial) condensates of water-soluble aminosilanes.
EP 186265 A and EP 68671 A describe compositions which contain (1) a mixture of a salt (A) of an organopolysiloxane having at least one amino group and at least one reactive group —OX, in which X is a hydrogen atom, alkyl radical or alkoxyalkyl radical, with (B), an organosilicon compound soluble in (2) and having at least two reactive groups —OX, and (2) a water-soluble solvent. The aqueous dilutions of these compositions do not have sufficient stability of the active substance.
EP 242798 A describes aqueous emulsions which contain, as emulsifiers, the salt of a water-soluble organic or inorganic acid and polysiloxane which, in addition to other siloxane units, contains siloxane units which have monovalent, SiC-bonded radicals comprising basic nitrogen in amounts of at least 0.5 percent by weight of basic nitrogen, based on the weight of the polysiloxane. As is known, such emulsions are not stable to dilution over a relatively long period.
EP 556740 A describes organopolysiloxane compositions which contain a salt of a water-soluble organic or inorganic acid and an organopolysiloxane which has at least one SiC-bonded organic radical comprising basic nitrogen. Such compositions have an active substance which is stable on dilution but are not adequate in their water-repellant effect.
U.S. 2004/0029981 A describes the treatment of fibers with emulsifier-free emulsions of amino-functional silicone oils.